KIEV, Ukraine — A month before Donald Trump clinched the Republican nomination, one of his closest allies in Congress — House Majority Leader Kevin McCarthy — made a politically explosive assertion in a private conversation on Capitol Hill with his fellow GOP leaders: that Trump could be the beneficiary of payments from Russian President Vladimir Putin.

“There’s two people I think Putin pays: Rohrabacher and Trump,” McCarthy (R-Calif.) said, according to a recording of the June 15, 2016 exchange, which was listened to and verified by The Washington Post. Rep. Dana Rohrabacher is a Californian Republican known in Congress as a fervent defender of Putin and Russia.

House Speaker Paul D. Ryan (R-Wis.) immediately interjected, stopping the conversation from further exploring McCarthy’s assertion, and swore the Republicans present to secrecy.